Battery sealing and component connecting method

ABSTRACT

A NON-AQUEOUS HERMETICALLY SEALED BATTERY CELL COMPRISING AN ELECTRODE ASSEMBLY AND AN ANHYDROUS LIQUID ELECTROLYTE IS FORMED BY NECKING A METAL CASING, CLOSED AT ONE END, A PREDETERMINED DISTANCE FROM THE OTHER END AND SEATING UPON SAID NECK AN ASSEMBLY INCLUDING A THRUST RING, AN INSULATING MEMBER, AND A METAL CAP. THE OPEN END IS THEN UNIFORMLY UPSET OR CRIMPED TO BEAR UPON SAID INSULATING MEMBER AND CAP, THEREBY HERMETICALLY SEALING THE ASSEMBLY. A FEATURE OF THE INVENTION CALLS FOR THE PASSING OF AN ELECTRODE-COUPLED CONDUCTOR BETWEEN THE THRUST RING AND NECK PRIOR TO UPSET TO THEREBY FORM A MECHANICALLY AND ELECTRICALLY SECURE ELECTRODE CONTACT. THE BATTERY IS FILLED WITH ELECTROLYTE THROUGH A NIPPLE IN THE CAP WHICH IS THEN COLD WELDED.

May 7, 1974 B. E.'JAG1D 3,809,580

BATTERY SEALING AND COMPONENT CCNNECTNG METHOD Filed June l, 1971 i @MKM United States PatentO U.S. Cl. 136-133 7 ABSTRACT OF THE DISCLOSURE A non-aqueous hermetically sealed battery cell comprising an electrode assembly and an anhydrous liquid electrolyte is formed by necking a metal casing, closed at one end, a predetermined distance from the other end and seating upon said neck an assembly including a thrust ring, an insulating member, and a metal cap. The open en d, is then uniformly upset or crimped to bear upon said insulating member and cap, thereby hermetically sealing the assembly. A feature of the invention calls for the passing of an electrode-coupled conductor between the thrust ring and neck prior to upset to thereby form a mechanically and electrically secure electrode contact. The battery is lled with electrolyte through a nipple in the cap which is then cold welded.

This invention relates generally tothe hermetic sealing of battery cells and in particular to an arrangement for simultaneously insuring against the 'release of battery electrolyte and gases, and insulating the positive from the negative terminals. i 'y 7 The art is replete with arrangements for hermetically sealing and simultaneously insulating the `opposite terminals of a battery. Recent advances in the battery art, however, have ledto significantly more stringent sealing requirements. These recent innovations include cells having electrolytes such as ammonia and sulfur dioxide with high vapor pressurey gases.' Complications arise because of the subjection of such batteries to storage at temperatures anywhere between those naturally occurring in'the'arctic and those at the equator, thereby multiplying included gas pressures. f

With respect to such cells, even the most advanced of the conventional sealing arrangements has proved to be hermetically ineffective. One such arrangement'which is reliable for more conventional battery types (and even alkaline and nickel cadmium batteries) includes a necked tube, the necking part acting as a rim upon which the metal cover and an overlapping" insulating collar are tightly clamped by a crimped or deformed casingfedge. U.S. Pat.l No. 3,279,953 relates to afurther improvement which eiects a projection of the necking both inwardly and towards the crimped end. This is achieved by 'precise non-symmetrical necking dimensions. While such advances Patented May 7 1974 z y to 1,600 this rate at a temperature which is substantially elevated C.). At room temperature, the seal is eifec` tively hermetic and leakage is diflicult to measure.

Accordingly, it is the object of this invention to provide a highly reliable insulating and virtually hermetic seal for use on cylindrical battery casings to prevent the escape of high vapor pressure gases such as ammonia andsulfur dioxide.

It is a further object of this invention to provide a seal for the aforementioned purpose which is inexpensive as to materials, relatively non-critical as to tolerance, and easily formed using mass production techniques.

f It is a further object of this invention to provide such a seal without obviating theuse of conventional'electrolyte filling techniques. f

Briefly, the invention is predicated upon the concept of initiallyseating a thrust ring upon the neck portion of a metallic tube casing, thereby obviating any close tolerance` requirements directed to the neck itself, it being sufficient if the ring, under the pressure to be applied, cannot be forced past the neck. The crimping or deforming o f the outer casing end over the insulator is then effected at an acute angle to the axis, whereby the end 4flange is not only inward, but is downward towards the closed end of the casing. With such an arrangement, increased gas pressure creates a greater bite in the insulator rather than any movement of the component parts and consequent release of gas.

It is a feature of the invention that since the entire seal is now substantially effected at the extreme end, it is possible'to use `t he crimping pressure to simultaneously eifect anfelectricalcntact between the shell neck and the thrust ing,'thereby obviating conventionalwelding techniques employed to electrically and mechanically connect one electrodeto the shell. Because the invention requires little to no ,modication of the cap, it is possible to use a nipple cap allowing the battery to be filled by injection and sealed by conventionall cold weld techniques.

lfhe above mentioned and other features and objects ofV ,this invention and the manner of attaining them will become-'more apparent and the invention itself will best be understood by reference to the following description ofian embodiment of the invention taken in conjunction with the accompanying drawings, the description of which follows, 'wherein FIG. 1 is a sectional view of the battery components positioned prior to ll and prior to deformation of the open end;

2 illustrates one arrangement for forming the neck Vportion of the battery caseg.

.FIG.'3 `is a sectional view of the sealed, filled battery cell; and l y f FIG. 4 illustrates, in partial section, an apparatus which may be utilized to uniformly deform the open end of the battery casing.

Turing now to FIG. 1, the positioned components may ,bev seen prior to the deformation or crimping of the outer edge of the `battery case. The battery shell 10 comprises acylindricalfmetal casing colsed at one end 11 and includinga neck 12 formed a predetermined distance from the other or open end. Neck 12may be easily formed as shown in FIG. 2 by the use of male and female dies 14 and 16, respectively, urged in the directions of the arrows 15` and 17 while being rotated about the axis of the 19/1000 inches, and requires a die pressure of several hundred pounds force to effect the desired necking.

The thrust ring 20 is dimensioned to be slidably received in the open end of the cell casing and to rest upon the necked portion 12. The thrust ring is preferably metallic so that it is (a) light and strong, providing a good thrust bearing surface, and I(fb) so that it forms a good electrical contact. A preferred outside ring diameter is a'fewi-thou'sandth's smaller'than the insiclell diameter of the cell"easing'.;As may be seen, thrust ring 20 serves as a platform-for'the cup shaped sealing member 22.` Sealingy and insulatingmember 22 includes a'pair of slots 23 and 24, they formel-'being centrally disposed to permit injected entryy of electrolyte into'lthey 4cellyandtthe latter-beingv provided for-passageof-an :electrode vle ad.35.y Recess 27 accommodates conventional accordian pleats inl the electrode contact 35- sof-that. it "is providechtlrust pressure upon the-metal cap30 when the assembly-hasultimately been crimped or :deformed to vproduce the hermetic seal: Thus, sealing member 22 simultaneously?K servesas'the hermetic sealing material and the velectrical insulator vibetween the. electrically `negative `cellfcasingv 10 and-the electrically positive cell cap 30. v J 'c As mayI be.y seen, thesealing member extends slightly beyondhtheendyof-.the casing to-'ensure that uponwthecrimpingor deformation of .the Vlatter-.,f-:the casing 12 :will noti contact the fcap 30. Cap4 30 includes `:afnipplev 31: through which the electrolyte is passed once the battery is hermetically sealed. l

An exemplary electrode assembly and l electrolyte (shown only in phantom in FIG. l) includes the following components in jelly roll fashion. The negative electrode comprises a lithium metal pressed onto a fine copper screen (anecter) which is separated from the cathode by a separator of porous polyethylene. Such a. separaton. in addition to providing inter-electrode insulation, permits adequate access of the electrolyte to the .electrode faces and enables the ionic transport within the cell. The cathode is a passive electrode formed of conductive carbon mixed with .glass fibers and polytetraiiuoroethylene which acts as a binder, the mixturefbeing pressed into a fine aluminum screen which acts as a cathecter` Lead wires 34 and 35which are preferably iiatand elongated, are ledrespectively betweenthe casingneck 12 and thrust ring 20 and through aperture 24 where it is accordian pleated by conventional mean s 1 where it is welded to cap member 30. u

.The preferred anhydrous liquid electrolyte ycomprises asolvent liquid sulfur dioxide and a cosolvent anhydrous organic liquid such as methylformate. One molofrlithiin bromide, is dissolved in the velectrolyte..,'Ihe electr vlyte solution is. pressure injectedinto the,v Icell. throu 31 in the conventional manner oncei th..hermet has .been effected (as .will be explained),`

lOnce theseal components .have been'positio'n shown inl-TIG.Y 1, the top -Yportion of the casing formed inwardly and downwardly toward ,theclosed, We have'found that in order to effect the Av1hi est degree of seal, it is desirable to deforni of the casing an angle delta of between an "2 5 angle of 10 has proven most satisfactory.andzprovids the optimum bite of the casing endinto't insulting member 2v2. v j

As maybe seen by a comparison ofiFIQS.' 1 and.`3, deformation of the end has effected a 'cliaps'e 'of the neck portion 12. This is not a requisite, b titis preferable where the pressure contact is to be formed tforelectr'o'de lead 34. One means for effecting sucha collapse Y'and'sirhulH t'n'eusly roll overv the' vend to'y the desired angle is shown in1FIG..4."'In"FIG. 4, a pair of dies 40'and"41" are provided.' The casing is placed in"receivingidie=401and upsetting die I41'is placed over the openfcasing end` and into the recess 42. With'die 40 stabilzedand' pressure exerted on die 41, the dies are forced together until ultimately complete mating of the dies is effected as shown *inthe iigurewnentthis'position is'r'e'ached; die 41 is seated upon the shoulder 43 of die 40.

The lower end of die 41 is preferably formed with an 5 annular recess 45 which effects the desired deformation attitude (Le. Since the total restraining force on the casing appears at the bottom 46, neck 12 collapses. It would be apparent to those skilled in the art that the same crimping or deformation of the open end may be effected without collapsing f the neck by supporting the shell at the neck during the deformation. Member 47 is provided to permit easy vseparation of the dies after the deforming operatio'nby the tapping of'i ts extended end 48.

I have found that thev amount of' force exerted on the plasticy (insulating portionof the seal and, therefore, "the degree of c ell leakage.. suppression) is a "function of the distance between the neck and the sealed end. It is thus relatively easily controlled.V 1

Materials used for the seal should have a low vapor transmission rate with respect to theV electrolyte materials and gases sealed therein-andfrelatively lowcold ow characteristics at elevatedtemperatures of for example -|-l 60\ F. Exemplary materialsare polypropylene, polyethylene, polysulfone, polyphenylen'e.. oxide, 4and other high temf perature high density plastics. f ,While the principles of the invention have been describedin connection with specific apparatus, it is to be clearly. understoodthat this description is made only by way vof example and not as a limitation V,to the scope of the invention.

What is claimed is:

1. A sealed battery cell including an electrode assembly of at least two lopposite polarity electrodes and a high vapor pressure electrolyte comprising:

a cylindrical metal casing closed at one end, open at the opposite end, and having a shallow necked p0rtion at a predetermined distance from its open end;

' rigid thrust ring providing a thrust bearing surface slidably'engaged within said cylindrical casing and y-in axial and abutting'relationship with said necked portion; -v g l a separate resilient annular sealing member in axial and inysuperposed abutting relationship with said thrust -Y ringrandm Y l .a metalcapdisposed across rthe open-end of said casing `and-hermetically seated along its outer periphery in achannelfformedby said resilient sealing member, v. theopen end of said metal casing being deformed y. uniformlyinwardly to bear upon said sealing mem- '5o' ber, the latterv being thus spatially-stabilized by and pressed against .a platform formed b-y said thrust -ringkthereby' sealing said battery against slow leakage of small quantities of said high vapor pressure electrolyte-fw The sealed batterycell claimed in claim 1, wherein saidf-sealing member comprises'a disc having an aperture thereindntegral with the annularportion thereof.

The sealed-tbattery.cell claimedl in claim .1, wherein the opensendof said metal 4casing -is deformed uniformly inwardly and atkan acute yangle tothe casing axis, to

therebybite annularly into. said-sealing member. ;.4;,"-I'hefsealed battery, cell claimed in claim 3, wherein s aid.acuteA angle is between.65'-and 85. f.:'S.---'1 `he'sealedv battery'cell' claimed in claim 3, wherein said yacuteaangle is approximately 80. ."-6.*The sealed battery-cell claimed in claim 3, wherein said-electrode assembly comprises a negative leadvaixed thereto,-saidtnegative lead including a substantially at f1 elongated member-disposed between said thrust ring and 70 said mele-whereby an electrical lpressure contact is formed hetweenxsaidk electrodey and the metal casing. v. ..The sealed,batt eiy cell claimedin claim @wherein ysaid metal comprises a nipple sealed by cold welding perpiin thefflling ,of said ',bat'tery with electrolyte.

(References on following page) References Cited UNITED STATES PATENTS Urry 136--107 Flynn 136-133 Feldhake 136-133 Fraiolo 136--162 Psuchida et al. 136-107 Larsen 136-107 Warren et al 136-83 R Jost 136-102 ALLEN B. CURTIS,

Rao 136-83 R Ruben 136-107 Morehouse 136-107 Ruscetta et a1 136-133 Lee 136-133 Seavey et al. 136-133 Primary Examiner C. LEFEVOUR, Assistant Examiner 

